Referring to FIG. 1, work products 100, including food products, are cut or otherwise portioned into smaller portions by processors in accordance with customer needs. Also, excess fat, bone, and other foreign or undesired materials are routinely trimmed from food products. It is usually highly desirable to portion and/or trim the work products into uniform shapes, thicknesses, and/or sizes, for example, for steaks to be served at restaurants or chicken fillets used in frozen dinners or in chicken burgers. Much of the portioning/trimming of work products, in particular food products, is now carried out with the use of high-speed portioning systems. These systems, for example, system 101 schematically shown in FIG. 1, use various scanning techniques to ascertain the size and shape of the food product as it is being advanced on a moving conveyor 102. This information is analyzed with the aid of a computer 104 to determine how to most efficiently portion the food product into optimum sizes, weights, or other criteria being used. For example, a customer may desire chicken breast portions in a certain shape or two different weight sizes, but with no fat or with a limited amount of acceptable fat. The chicken breast is scanned as it moves on a conveyor belt 106 and a determination is made through the use of a computer as to how best to portion the chicken breast to the shape and weights desired by the customer, so as to portion the chicken breast most effectively. Work products are also scanned for sorting the work products, to verify that the work product is being processed properly to track production volume, and to control upstream and downstream equipment.
Portioning and/or trimming of the work product can be carried out by various cutting devices such as cutters 108 and slicers 110. Once the portioning/trimming has occurred, the resulting portions are off-loaded from the cutting conveyor and placed on a take-away conveyor for further processing or, perhaps, to be placed in a storage bin.
Portioning systems of the foregoing type are known in the art. As typical, the portioning system includes a conveyor that carries work products past a stationary scanning station 112 associated with the conveyor, whereat the work products are scanned to ascertain selected physical parameters, for example, their size, shape, and thickness, and then determine their weight, typically by utilizing an assumed density for the work products. In addition, it is possible to locate discontinuities (including voids), foreign material, and undesirable material in the work product, for example, bones or fat in a meat portion. Also, as noted above, scanning can determine if the work product is being processed properly, track production levels or volume, control production equipment, and assist in sorting the work products.
The scanning can be carried out utilizing a variety of techniques, including a video camera to view a work product illuminated by one or more light sources. Light from the light source is extended across the moving conveyor belt to define a sharp shadow or light stripe line, with the area forwardly of the transverse beam being dark. When no work product is being carried by the infeed conveyor, the shadow line/light stripe forms a straight line across the conveyor belt. However, when a work product passes across the shadow line/light stripe, the upper, irregular surface of the work product produces an irregular shadow line/light stripe as viewed by a video camera directed downwardly on the work product and the shadow line/light stripe. The video camera detects the displacement of the shadow line/light stripe from the position it would occupy if no work product were present on the conveyor belt. This displacement represents the thickness of the work product along the shadow line/light stripe. The length of the work product is determined by the distance of belt travel that shadow lines/light stripes are created by the work product. In this regard, an encoder is integrated into the infeed conveyor, with the encoder generating pulses at fixed distance intervals corresponding to the forward movement of the conveyor.
In lieu of a video camera, the scanning station may instead utilize an x-ray apparatus for determining the physical characteristics of the work product, including its shape, mass and weight. X-rays may be passed through the object in the direction of an x-ray detector. Such x-rays are attenuated by the work product in proportion to the mass thereof. The x-ray detector is capable of measuring the intensity of the x-rays received thereby after passing through the work product. This information is utilized to determine the overall shape and size of the work product, as well as the mass thereof. An example of such an x-ray scanning device is disclosed by U.S. Pat. No. 5,585,603, incorporated by reference herein.
The data and information measured/gathered by the scanning devices is transmitted to computer 104, preferably on board the portioning apparatus, which records the location of the work product on the conveyors as well as the shape, size, and other parameters of the work product. With this information, the computer can determine how to optimally cut or portion the work product at the portioning station, whether processes need to be changed or adjusted, if production levels or volumes are acceptable, and if upstream or downstream equipment needs to be adjusted.
Automatic portioning systems are expensive, as is the labor to continuously load and unload them. One of the keys to economical production using automatic portioning is to keep the conveyor belt full of properly spaced work product. Any gaps in loading the conveyor belt entering the portioner are wasted production potential, and cost as much as if work product were being processed. Small gaps in the continuous arrival of product to the automatic portioning apparatus can occur for various reasons, including: problems in upstream processes; material handling delays such as putting the next tote of work product into place; the inattention of loading employees; poor quality product that employees need to reject; and automatic sorting equipment upstream that sorts into multiple streams according to a randomly varying work product attribute.
While buffering functions are common in processing lines handling rigid products such as beverage containers, or continuous products such as liquids, they are unknown to the present inventors in processing of wet, conformable, naturally random work products such as boneless chicken breasts or fish fillets, except as large bins of work product that are subsequently loaded again onto a conveyor belt. An additional requirement for a buffer in front of an automatic portioning apparatus is that the work product maintains its orientation on the conveyor belt such that it is not flipped, rotated or folded as might occur when using a storage bin as a buffer. This is important for minimizing loading labor leading into the automatic portioning apparatus.